There are many reasons for concern about the GCSB Bill that has just passed into law, but one we might not have expected is the extent to which the Prime Minister seems unaware of its true implications.

It must surely have come as a shock, even to his supporters, that John Key seems not to understand some of the basic principles of democratic government. In particular, he seemed to see no distinction between his own personal assurances and the law of the land.

The great principle of English common law, both foreshadowing and endorsed by the Glorious Revolution, is that no man “be ye ever so high” is above the law. The great Chief Justice Edmund Coke would have made short shrift of any pretension that a mere politician could decide what was and was not the law by his mere say-so.

Yet that is what our Prime Minister apparently presumes to do. In assurances given in a television interview, he asked citizens to accept his word as to his intentions concerning the new power to intercept our communications that the security service he heads was about to have conferred upon it. He seemed to think that, merely because he had said it, it was equivalent to a legal obligation and could be relied upon in a court of law.

He was under a similar misapprehension when he proclaimed that he would speak in the Bill’s Third Reading debate so that future courts would know what the Act meant and, therefore, what the law was. He did not seem to realise that it is Parliaments, not Prime Ministers, that make law and that it is courts that interpret it.

But surely, it may be objected, we can trust John Key? If he says he will use the new power responsibly, why should we not believe him?

Let us leave to one side the obvious point that, however virtuous John Key may be, he will not be here forever, and we have no idea what view his successors may take, or what use they might make, of the wide powers he has claimed for himself.

The real point, though, is that liberty can be eroded if power is placed in just one set of hands, however well-intentioned, and is not subject to proper checks and safeguards – and that almost always means legal safeguards. It needs only a temptation to treat as identical or equivalent the interests of a particular party or government on the one hand and those of the whole country on the other to raise unacceptable risks that basic freedoms might be threatened.

Some of the most thorough-going despots in history have no doubt believed that the fortunes of their country and their own are indistinguishable. I have no doubt that Robert Mugabe, for example, genuinely believes that Zimbabwe would be a shambles without him.

Our own Prime Minister’s reliability in this regard is surely called into question by his easy assumption that his own (personal, political and partisan) interests are the only guide necessary to ensure that the huge diversity of interests of his fellow citizens is properly served.

The rationale offered by Peter Dunne for his own support for the Bill offers no more comfort. If the Prime Minister were to misuse these powers, Peter Dunne assures us, John Key would be “punished by public opinion”. Leaving aside the question of how the public would ever know, what makes Peter Dunne think that John Key is deterred by public opinion? If public opinion counted for anything, we wouldn’t have the Bill in the first place – and nor, for that matter, would we have Peter Dunne.

Perhaps the most worrying aspect of the whole episode – going beyond even the very real fears about our progress down a slippery slope to a surveillance state – is what it tells us about the Prime Minister’s increasingly slapdash way of doing business.

He seems more and more to believe that he can get away with flying by the seat of his pants – that he is able to resolve any problem with a quick fix or an easy promise. His government seems increasingly to be a law unto itself, answerable to no one but the Prime Minister himself, and he looks to be more and more prone to taking his eye off the ball.

The literally overnight timeframe of the foreign exchange dealer may have been ideal for the purpose of making a quick personal fortune on the foreign exchange markets, but we surely need a longer and more considered timeframe and a more thoughtful approach from the country’s leader.

The GCSB saga has been a shambles from beginning to end. Perhaps the only consolation is that it begins to offer us some explanation as to why so much else suddenly seems to be going wrong as well.